Ok, you somehow went to 13 on the demo? If i recall, the test with 2 cubes, and an energy ball. So its a weird glitch that you did. Since it never intended for you to go there in the demo, it doesnt complete the map and replaces the wall with the glitch wall. Is it still there? please make a video of it.

I just had the same thing happen.......i went to chamber 11, got the dual portal gun, which you COULDN'T do before the update.......then, i did chamber 12, then.........the friggen trippy wall was there.....I almost seizured. Don't make the man do it again to record it.......so.............COLORFUL!!!!!!!!!! oh.....

ohhhh i know what your talking about, i remember ♥♥♥♥ing with portal one time and then crawling in to this thin place where these moving platforms come out and in, (test chamber 15) went i looked around its all glitchy and light and colorful. but what update? a new one? because in the demo i remembered you got the dual portal gun in test chamber 11 and then it stops, or lets you finish the chamber. Are you going to report this bug or something? i cant even try it out because i got the full game a while ago.

Yeah. My Portal First slice updated and then i went to play it, it let me go to test chamber 12, which played normally......then i was confronted wit the glitch wall. I'll post a screenshot. For science.